Carburetor utilizing fluidics

ABSTRACT

A carburetor whose main fuel flow system is constructed by a jet deflection proportional fluid amplifier. The carburetor has a separate fluid amplifier adapted to inject a fuel for use in a slow fuel flow system by means of a negative pressure in proportion to the amount of air passing through a throttle valve opening.

United States Patent Ishida [54] CARBURETOR UTILIZING FLUIDICS [72] Inventor: Takashi lshida, Ohi-Machi, Japan [73] Assignee: Mikuni Kogyo Co., Ltd.,

Japan [22] Filed: Aug. 17, 1970 [21] Appl. No.: 64,286

Tokyo,

[30] Foreign Application Priority Data Aug. 18, 1969 Japan ..44/65229 [52] US. Cl. ..26l/36 A, 26l/DIG. 69, l37/81.5,

261/69 R, 261/41 R, l23/D1G. 10 [51] Int. Cl. ..F02m 69/04 [58] Field of Search..26l/DIG. 69, 36 A, 69 R, 41 R;

[56] References Cited 1 UNITED STATES PATENTS 3,288,446" 11/1966 Bimberg 261/41 D [15] 3,690,625 [451 Sept. 12, 1972 3,389,894 6/1968 Binder 261/69 R 3,406,951 10/1968 Marks ..26l/DIG. 69 3,556,488 1/1971 Arikawa et a1 ..261/DIG. 69 3,570,823 3/1971 Arikawa et a1 ..261/D1G. 69 3,574,346 4/1971 Sulich ..26l/D1G. 69

Primary Examiner-Tim R. Miles Attorney-McGlew and Toren [57] ABSTRACT A carburetor whose main fuel flow system is constructed by a jet deflection proportional fluid amplifier. The carburetor has a separate fluid amplifier adapted to inject a fuel for use in a slow fuel flow system by means of a negative pressure in proportion to the amount of air passing through a throttle valve opening.

1 Claim, 2 Drawing Figures P'ATE'NTED SEP 12 m2 fuel FIG.2

fuel

INVENTOR ISM DR 7! Era Tmmsm ATTORNEY CARBURETOR UTILIZING FLUIDICS The present invention relates to a carburetor utilizing fluidics.

Heretofore, it has been well known to make use of a jet deflection proportional fluid amplifier so as to construct a main fuel flow system of a carburetor. In such a carburetor only one jet deflection proportional fluid amplifier (hereinafter abbreviated as fluid amplifier) is adapted to be used throughout the total operation range of an engine from an instant when the engine is operated under the idling operation to an instant when the engine is operated under the high speed condition with fully opened state of a throttle valve.

FIG. 1 shows one example of the above mentioned conventional carburetor. The carburetor comprises a fluid amplifier which includes a deflection flow passage connected to a fuel injection nozzle 16 opened to a Venturi member 17 and a control flow passage 18 connected to a negative pressure detecting nozzle 19.

i The fluid amplifier 10 is provided at its substrate 11 with a main jet supplying port 12 connected at both sides thereof with control ports 13a and 13b, respectively. The main jet supplying port 12 is connected through an interaction region 14 to output flow passages 15a" and 15b, respectively. The deflection flow from the output flow passage 15a is supplied to the fuel injection nozzle 16 while the fuel from the output flow passage 15b returns to a fuel tank T. 36 designates a throttle valve.

In the construction shown in FIG. 1, when the degree of opening of the throttle valve 36 becomes small and the number of revolutions of the engine is small, that is, when the engine is operated under no load or light load condition the flow speed of air passing through the Venturi member 17 becomes low so that the negative pressure to be detected by the negative pressure detecting nozzle 19 becomes very low and substantially zero. Thus, the amount of the deflection flow supplied from the main jet supplying port 12, of the fluid amplifier 10 to the output flow passage 15a becomes substantially zero with the result that aproper amount of the fuel flow satisfying the engine operation could not be obtained.

An object of the invention is to provide such a carburetor comprising a control negative pressure circuit constructed by a fluid amplifier for use under a light load condition so thata properarnount of fuel flow can be obtained throughout the total operation range of the engine from an instant when the engine is operated under the idling condition to an instant when the engine is operated under the high. speed condition with fully opened state of a throttle valve. The above mentionedobject can be attained by a carburetor whose main fuel flow system is constructed by a jet deflection proportional fluid amplifier characterized in that provision ismade for a separate fluid amplifier adapted to inject a fuel for use in a slow fuel flow system by means of a negative pressure in proportion to the amount of air passing through a throttle valve opening.

Other and further objects and advantages of the invention will be readily apparent from the following descriptions and a drawing in which:

FIG. 1 is a sectional view showing a conventional carburetor utilizing fluidics; and

FIG. 2 is a sectional view showing a carburetor according to the present invention.

A carburetor in one embodiment of the invention comprises two fluid amplifiers 10 and 20 as shown in FIG. 2.

The first fluid amplifier 10 comprises a main fuel flow system which is the same in construction as the conventional fluid amplifier shown in FIG. 1.

The second fluid amplifier 20 comprises a slow fuel flow system 35 including a deflecting flow passage 25a connected through a passage 26 to a fuel injection nozzle 29 adapted to be opened to a Venturi member 17 and including a control flow passage adapted to be opened to a portion corresponding to a pilot passage 0 a conventional carburetor.

The second fluid amplifier 20 is provided with a deflecting flow passage 25b which returns to a fuel tank T.

24 is an interaction region connecting a main jet supplying port 12 and the flow passages 25aand 255.

A. negative pressure passage 28 connected to a control port 23av is provided at its intermediate portion with a reduced section 27 and provided at its end with a boost hole 31 and negative pressure holes 32 and 33. The boost hole 31 is adjusted by a screw 30. The negative pressure holes 32 and 33 are arrangedadjacent to the boost hole 3lfand are adapted to be operated to stop compensating fuel supplied to the nozzle 29 when a throttle valve 36 is closed and to inject the fuel from the slow fuel flow system 35 in proportion to a slight opening of thethrottle valve 36.

The negative pressure passage 28 is provided immediately after itsreduced section 27 with a negative pressure drop down screw 34 whichis connected to an air inlet 37 arranged at one side of the screw 34.

As stated hereinbefore, the carburetor shown in FIG. 2 comprises the first fluid amplifier l0 constituting a main fuel flow system and the second fluid amplifier 20 whose circuit is connected to the control port 234 adapted to receive negative pressure for deflecting a main jet stream through a circuit which is substantially the same as the slow fuel flow system of the conventional carburetor.

The boost hole 31 and the negative pressure hole 32 correspond to so'called pilot outlet bypasses, respec tively, of the conventional carburetor. The boost hole 31 and negative pressure hole 32. serve to adjust the degree of negative pressure to be introduced into the negative pressure passage 28 with the aid of the adjusting screw 30. 'Ihe negative pressure hole 32 serves to detect the negative pressure generated due to the speed of air stream passing through the throttled portions in response to the degree of opening of the throttle valve The screw 30 adjusted and the position, numbers, diameter etc. of the negative pressure holes of the slow fuel flow system 35 ensure a generation of the negative As seen from the above, the addition of the separate fluid amplifier 20 to the first fluid amplifier makes it possible to properly adjust the amount of fuel flow when the engine is operated at no load or low load condition. The above mentioned construction is also capable of properly adjusting the amount of fuel flow in an easy manner when'the engine is operated at light load or partial load condition.

As stated hereinbefore, the conventional carburetor whose fuel system is constructed by one fluid amplifier only has a considerable difliculty in obtaining a proper amount of fuel flow both when the engine is operated under no load or light load condition and when the engine is operated under heavy load condition, whereas the addition of a separate fluid amplifier for use under the light load condition to the conventional fluid amplifier so as to construct a control negative pressure circuit according to the invention provides the important advantage that a proper amount of fuel flow can be obtained throughout the total operation range of the engine from an instant when the engine is operated under the idling condition to an instant when the engine is operated under the high speed condition with fully opened state of the throttle valve.

What is claimed is:

1. A carburetor comprising first means forming a main fuel flow system, said first'means including a tubular flow duct for the passage of air therethrough, a Venturi member providing an annular constriction in said flow duct intermediate its ends, a throttle member positioned in said flow duct downstream in the direction of air flow therethrough from said Venturi member, a first jet deflection proportional fluid amplifier, a fuel injection nozzle opening into said flow duct at the location of said Venturi member, an output flow passage connecting said first fluid amplifier to said fuel injection nozzle, a negative pressure detecting nozzle opening into said flow duct at the location of said Venturi member, a control flow passage connecting said negative pressure detecting nozzle to said first fluid amplifier, wherein the improvement comprises second means forming a slow fuel flow system separate from said main fuel flow system, said second means including a second jet defection proportional fluid amplifier for injecting fuel into said flow duct, a second fuel injection nozzle opening into said flow duct at the location of said Venturi member for injecting fuel into said duct, a deflecting flow passageway connecting said second fuel injection nozzle and said second fuel amplifier, a negative pressure passage connected between said flow duct downstream from the position of said Venturi meter at the location of said throttle member for detecting the negative pressure generated by the speed of the air stream passing through the throttle portion of said flow duct for supplying fuel to said flow duct through said deflecting flow passage separate from the supply provided by said first fluid amplifier, said second fluid amplifier comprising an interaction chamber, a main jet supply port for introducing fuel into said interaction chamber, one end of said negative pressure passage connected to said main jet supply port upstream from said interaction chamber and three branch passages arranged in parallel extending between the other end of said negative pressure assage and said flow dufit at the location of said throtfie member within said ow duct, two of said branch passages forming negative pressure holes and the third branch passage forming a boost hole, said negative pressure passage having a constricted section intermediate its ends, an air inlet conduit connected to said negative pressure passage adjacent said constricted section on the side thereof remote from said main jet supply port, an adjustable negative pressure drop-down screw positioned in said air inlet conduit, an adjusting screw positioned within said branch passage forming said boost hole so that by means of said adjusting screw the branch passage forming the boost hole and the adjacent branch passage forming a negative pressure hole serve to adjust the degree of negative pressure introduced into said negative pressure passage. 

1. A carburetor comprising first means forming a main fuel flow system, said first means including a tubular flow duct for the passage of air therethrough, a Venturi member providing an annular constriction in said flow duct intermediate its ends, a throttle member positioned in said flow duct downstream in the direction of air flow therethrough from said Venturi member, a first jet deflection proportional fluid amplifier, a fuel injection nozzle opening into said flow duct at the location of said Venturi member, an output flow passage connecting said first fluid amplifier to said fuel injection nozzle, a negative pressure detecting nozzle opening into said flow duct at the location of said Venturi member, a control flow passage connecting said negative pressure detecting nozzle to said first fluid amplifier, wherein the improvement comprises second means forming a slow fuel flow system separate from said main fuel flow system, said second means including a second jet defection proportional fluid amplifier for injecting fuel into said flow duct, a second fuel injection nozzle opening into said flow duct at the location of said Venturi member for injecting fuel into said duct, a deflecting flow passageway connecting said second fuel injection nozzle and said second fuel amplifier, a negative pressure passage connected between said flow duct downstream from the position of said Venturi meter at the location of said throttle member for detecting the negative pressure generated by the speed of the air stream passing through the throttle portion of said flow duct for supplying fuel to said flow duct through said deflecting flow passage separate from the supply provided by said first fluid amplifier, said second fluid amplifier comprising an interaction chamber, a main jet supply port for introducing fuel into said interaction chamber, one end of said negative pressure passage connected to said main jet supply port upstream from said interaction chamber and three branch passages arranged in parallel extending between the other end of said negative pressure passage and said flow duct at the location of said throttle member within said flow duct, two of said branch passages forming negative pressure holes and the third branch passage forming a boost hole, said negative pressure passage having a constricted section intermediate its ends, an air inlet conduit connected to said negative pressure passage adjacent said constricted section on the side thereof remote from said main jet supply port, an adjustable negative pressure drop-down screw positioned in said air inlet conduit, an adjusting screw positioned within said branch passage forming said boost hole so that by means of said adjusting screw the branch passage forming the boost hole and the adjacent branch passage forming a negative pressure hole serve to adjust the degree of negative pressure introduced into said negative pressure passage. 